The trio of congressional officials who have exclusive control over traffic rules on the Capitol grounds are ordering a change that would enhance Capitol Police’s authority to search backpacks, suitcases and other personal belongings carried onto the 290-acre property.

Under a section of code banning firearms, dangerous weapons and explosive devices, the language approved by the Capitol Police Board on July 15 states: “At the direction of the Chief of Police, the United States Capitol Police may search packages, bags, and other containers in the immediate possession of individuals who enter and are within the United States Capitol Grounds for the purpose of detecting prohibited items.”

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“Fourth-Amendment-Free Zone,” suggested Arthur B. Spitzer, legal director for the American Civil Liberties Union of the Nation’s Capital, after he reviewed the amendment.

“We’ve all gotten pretty much used to the idea that you have to do that when you’re entering any of the buildings of the Capitol — you go through a metal detector. Same at a court house or city hall,” Spitzer said. “That’s a different thing than just somebody who’s minding his own business, walking across the Capitol grounds. The Capitol grounds are open to the public.”